18 
DEVONIAN FAUNA. 
II. SuB-ORDER.— INTEaHIPALLIATA, d'Orbigny, 1843. 
I. Family. — CAEDiiDiK, Sioainson, 1837. 
1. Genus. — Conocardium, Bronn, 1835. 
Pletjroehtnohus, FJiiUips, 1836. 
Though this well-defined genus is evidently very nearly allied to Gardium, 
there seems much diversity of opinion as to the position of the animal in the 
shell. The truncated rostral end is regarded as the anterior side by most authors, 
e. g. M'Coy, Zittel, Fischer, and Barrois, the gape on the triangular side being, in 
that case, for the passage of the syphons. Tryon, on the other hand, comparing 
it with Adacna, regards it as inverted, and in that case the gaping end would be 
anterior and the aperture would be for the foot. It seems to me that the former 
is the most probable supposition, though something may be said for both views. 
The following descriptions, therefore, treat the rostral side as anterior. CEhlert 
refers it to the family Lithocardiidce of Munier Chalmas. 
It extends from the Silurian to the Carboniferous. 
For the purposes of description Barrois divides the test into the following 
regions from front to back : — 1, Rostrum ; 2, anterior cordiform slope ; 3, anterior 
keel ; 4, median region ; 5, median ridge ; 6, posterior slope ; 7, posterior sinus ; 
8, conical aliform protuberance. 
The species appear to be numerous, and as some of the earlier specific descrip- 
tions are very much generalised, it is far from easy to decide the synonymy. In 
the localities under notice the genus is well represented both in species and 
individuals. 
1. Conocardium clathratum, d'Orhigny. PI. I, figs. 17 — 20, and PL II, figs. 1 — 3. 
1834-40. Carditim alifoeme, QoJdfuss (pars), not Sowerly. Petref. Germ., vol. ii, 
p. 213, pi. cxlii, figs, a and g (only). 
1841. Pleueoehynchus alifoemis, Fhillips. Pal. Poss., p. 34, pi. xvii, fig. 51 ; 
and pi. Ix, fig. 51. 
1842. Caedium al^foeme, var. clatheattjm, d'ArcMac and de Verneuil. Geol. 
Trans., ser. 2, vol. v, pt. 2, p. 374, pi. xxxvi, 
figs. 7, 7 a. 
1843. PLEirEOEHYNCHUS AL^FOEMis, F. A. Romer. Verst. Harzgeb., p. 22, 
pi. vi, figs. 5 a — c. 
1849. CoKOCAEDiTJM CLATHEATUM, d'Orhigny. Prodrome, vol. i, p. 80. 
